RectTransform returning incorrect rect bounds

I have a UI element on a screen canvas that I update the position of to place next to an actor at a given world point. The UI element visually places itself correctly, but there is no change in the RectTransform's rect property -- though the transform's x position is changed, rect.x is 0 before and after the assignment. This prevents me from using updated bounds to position it away from other elements, as the returned bounds are very much incorrect. What could be causing this?